1. Field of the Invention:
The invention relates to a method of installing mineral fibre material containing a binder and provided in roll form in an elongated installation space bounded by lateral supports, particularly an area between two roofing spars or rafters, and also to a mineral fibre strip suitable for carrying out the method and a method of producing such a mineral fibre strip.
2. Discussion of Background Art
When insulating the space between rafters with mineral fibre material, one essential difficulty is that the strip or panel-shaped prefabricated mineral fibre material has to be manufactured and made available in clearly defined widths, but the distances between the rafters may, however, vary from one building site to another, and frequently--particularly in old buildings--even from one area of the rafters to another or even within the same area of the rafters. The mineral fibre material must be installed with a certain pressure between the rafters which is sufficiently great to avoid gaps along the edges, to prevent cold bridges and convection, and to achieve a retaining effect. On the other hand, the pressure should not be so great as to produce bulging of the material, which might unintentionally close off the rear ventilation gap and defeat the desired formation of a flat inside face to the insulation. Depending on the compressibility of the mineral fibre material, therefore, the oversize when installing should be in the range between 1 and 5 cm.
DE-OS No. 32 29 601 discloses a sheet of insulating material which permits proper installation even by inexperienced installers and substantially facilitates adaptation to the particular rafter width involved. Since this insulating material has no functional disadvantages compared with a normally fitting insulating material, either in installation or in effect, it has become commercially popular. Facilitation of fitting resides in the fact that there are in the lateral marginal zones of the layer of insulant differently colored marking lines which do not actually weaken the layer of insulant, being only visually identifiable, but which define modular marginal strips which can be cut off for adaptation to the relevant rafter width. Therefore, the user need only select the marking lines at which a cut is to be made, place a cutting aid between the layer of insulant and the lining and without any further aids such as a straight edge or the like, cut along the given marking line in a single stroke, needing only to ensure that the knife follows the marking line. However, it is always a disadvantage that cutting the insulating material to suit the desired rafter width will necessarily result in wastage.
To avoid wastage, it is also known, for example from DE-OS No. 32 03 624, to depart from a rectangular panel or strip shape and to use instead wedge-shaped insulating panels which are constructed, for instance, like a triangle. These wedge-shaped panels should be produced so as to be slightly undersized, installed individually between the rafters and wedged therein against adjacent panels which are fitted the other way around so that the desired pressure of contact is achieved. Wedging panels against one another in the area between the rafters does, however, create practical difficulties in the case of mineral fibre material because the spreading-apart wedging effect which must be achieved with such panels presupposes the panels sliding on the oblique surfaces of adjacent panels, but the consistency of mineral wool only allows this to occur to an extremely limited extent, if at all. Furthermore, if the triangular geometric height of the triangular panel (which runs at a right-angle to the longitudinal extension of the rafter area) does not happen to correspond to the distance between the rafters, then there is the further difficulty that a laterally projecting tip of one wedge of insulating material will be squashed on the rafter while an upwardly projecting tip will be squashed against the bottom of a panel. This results in localized accumulations of material which disturb the mutual contact between panel elements and will inevitably lead to gaps between adjacent panel edges, which will in turn produce cold bridges and convection. To avoid large projecting tips and the resulting gaps, its necessary to make available a multiplicity of nominal panel widths, which leaves the situation unchanged.
A further essential disadvantage of this method lies in the fact that the wedge-shaped mineral fibre panels must be packaged and delivered in stacks and cannot be rolled up. Mineral fibre strips which are stored and delivered in the form of rolls offer the advantage of considerably reduced space for transport and storage. Since the mineral fibre material is greatly compressed in the roll, and by reason of the pressure which takes effect in the roll shape, the material can be compressed without any localized irreversible squashing. With such mass produced items of low raw density, a reduction of, for example, a half in transport and storage volume provides quite perceptible cost advantages, and correspondingly saves on packaging material. Therefore, every attempt should be made to find a procedure by which the mineral fibre material can be packaged and delivered in roll form.